Deposition chamber and method for depositing low dielectric constant films

ABSTRACT

An improved deposition chamber ( 2 ) includes a housing ( 4 ) defining a chamber ( 18 ) which houses a substrate support ( 14 ). A mixture of oxygen and SiF 4  is delivered through a set of first nozzles ( 34 ) and silane is delivered through a set of second nozzles ( 34   a ) into the chamber around the periphery ( 40 ) of the substrate support. Silane (or a mixture of silane and SiF 4 ) and oxygen are separately injected into the chamber generally centrally above the substrate from orifices ( 64, 76 ). The uniform dispersal of the gases coupled with the use of optimal flow rates for each gas results in uniformly low (under 3.4) dielectric constant across the film.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.08/851,856, filed May 6, 1997, now U.S. Pat. No. 6,070,551, which is aContinuation-In-Part of U.S. patent application “DEPOSITION CHAMBER ANDMETHOD FOR LOW DIELECTRIC FILMS,” U.S. Ser. No. 08/647,619, filed May13, 1996, now abandoned having Shijian Li, Yaxin Wang, Fred C. Redeker,Tetsuya Ishikawa and Alan W. Collins as inventors and assigned toApplied Materials, Inc. The 08/647,619 application is herebyincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

One of the primary steps in the fabrication of modern semiconductordevices is the formation of a thin film on a semiconductor substrate bychemical reaction of gases. Such a deposition process is referred to aschemical vapor deposition (CVD). Conventional thermal CVD processessupply reactive gases to the substrate surface where heat-inducedchemical reactions can take place to produce the desired film. PlasmaCVD processes promote the excitation and/or dissociation of the reactantgases by the application of radio frequency (RF) energy to the reactionzone proximate the substrate surface thereby creating a plasma of highlyreactive species. The high reactivity of the released species reducesthe energy required for a chemical reaction to take place, and thuslowers the required temperature for such CVD processes.

In one design of plasma CVD chambers, the vacuum chamber is generallydefined by a planar substrate support, acting as a cathode, along thebottom, a planar anode along the top, a relatively short sidewallextending upwardly from the bottom, and a dielectric dome connecting thesidewall with the top. Inductive coils are mounted about the dome andare connected to a source radio frequency (SRF) generator. The anode andthe cathode are typically coupled to bias radio frequency (BRF)generators. Energy applied from the SRF generator to the inductive coilsforms an inductively coupled plasma within the chamber. Such a chamberis referred to as a high density plasma CVD (HDP-CVD) chamber.

In some HDP-CVD chambers, it is typical to mount two or more sets ofequally spaced gas distributors, such as nozzles, to the sidewall andextend into the region above the edge of the substrate support surface.The gas nozzles for each set are coupled to a common manifold for thatset; the manifolds provide the gas nozzles with process gases. Thecomposition of the gases introduced into the chamber depends primarilyon the type of material to be formed on the substrate. For example, whena fluorosilicate glass (FSG) film is deposited within the chamber, theprocess gases may include, silane (SiH₄), silicon tetrafluoride (SiF₄),oxygen (O₂) and argon (Ar). Sets of gas nozzles are commonly usedbecause it is preferable to introduce some gases into the chamberseparately from other gases, while other gases can be delivered to acommon set of nozzles through a common manifold. For example, in theabove FSG process it is preferable to introduce SiH₄ separately from O₂,while O₂ and SiF₄ can be readily delivered together. The nozzle tipshave exits, typically orifices, positioned in a circumferential patternspaced apart above the circumferential periphery of the substratesupport and through which the process gases flow.

As device sizes become smaller and integration density increases,improvements in processing technology are necessary to meetsemiconductor manufacturers' process requirements. One parameter that isimportant in such processing is film deposition uniformity. To achieve ahigh film uniformity, among other things, it is necessary to accuratelycontrol the delivery of gases into the deposition chamber and across thewafer surface. Ideally, the ratio of gases (e.g., the ratio of O₂ to(SiH₄+SiF₄)) introduced at various spots along the wafer surface shouldbe the same.

FIG. 1 illustrates a typical undoped silicate glass (USG) depositionthickness variation plot 46 for a conventional deposition chamber suchas the chamber described above. The average thickness is shown by baseline 48. As can be seen by plot 46, there is a relatively steep increasein thickness at end points 50 and 52 of plot 46 corresponding to theperiphery 42 of substrate 20. The center 54 of plot 46 also dips downsubstantially as well.

U.S. patent application Ser. No. 08/571,618 filed Dec. 13, 1995, thedisclosure of which is incorporated by reference, discloses how plot 46can be improved through the use of a center nozzle 56 coupled to a thirdgas source 58 through a third gas controller 60 and a third gas feedline 62. Center nozzle 56 has an orifice 64 positioned centrally abovesubstrate support surface 16. Using center nozzle 56 permits themodification of USG deposition thickness variation plot 46 from that ofFIG. 1 to exemplary plot 68 of FIG. 2. Exemplary deposition thicknessvariation plot 68 is flat enough so that the standard deviation of thedeposition thickness can be about 1 to 2% of one sigma. This is achievedprimarily by reducing the steep slope of the plot at end points 50, 52and raising in the low point at center 54 of plot 46.

With the advent of multilevel metal technology in which three, four, ormore layers of metal are formed on the semiconductors, another goal ofsemiconductor manufacturers is lowering the dielectric constant ofinsulating layers such as intermetal dielectric layers. Low dielectricconstant films are particularly desirable for intermetal dielectric(IMD) layers to reduce the RC time delay of the interconnectmetallization, to prevent cross-talk between the different levels ofmetallization, and to reduce device power consumption.

Many approaches to obtain lower dielectric constants have been proposed.One of the more promising solutions is the incorporation of fluorine orother halogen elements, such as chlorine or bromine, into a siliconoxide layer. It is believed that fluorine, the preferred halogen dopantfor silicon oxide films, lowers the dielectric constant of the siliconoxide film because fluorine is an electronegative atom that decreasesthe polarizability of the overall SiOF network. Fluorine-doped siliconoxide films are also referred to as fluoro silicate glass (FSG) films.

From the above, it can be seen that it is desirable to produce oxidefilms having reduced dielectric constants such as FSG films. At the sametime, it is also desirable to provide a method to accurately control thedelivery of process gases to all points along the wafer's surface toimprove characteristics such as film uniformity. As previouslydiscussed, one method employed to improve film deposition uniformity isdescribed in U.S. patent application Ser. No. 08/571,618 discussedabove. Despite this improvement, new techniques for accomplishing theseand other related objectives are continuously being sought to keep pacewith emerging technologies.

SUMMARY OF THE INVENTION

The present invention is directed toward an improved deposition chamberthat incorporates an improved gas delivery system. The gas deliverysystem helps ensure that the proper ratio of process gases is uniformlydelivered across a wafer's surface. The present invention is alsodirected toward a method of depositing FSG films having a low dielectricconstant and improved uniformity. This is achieved by a combination of(1) the uniform application of the gases (preferably silane,fluorine-supplying gases such as SiF₄ or CF₄, and oxygen-supplying gasessuch as O₂ or N₂O) to the substrate and (2) the selection of optimalflow rates for the gases, which preferably have been determined as aresult of tests using the particular chamber. In some embodiments, thedeposited FSG film has a dielectric constant as low as 3.4 or 3.3.Preferably, the dielectric constant of the FSG film is at least below3.5.

The improved deposition chamber includes a housing defining a depositionchamber. A substrate support is housed within the deposition chamber. Afirst gas distributor has orifices or other exits opening into thedeposition chamber in a circumferential pattern spaced apart from andgenerally overlying the circumferential periphery of the substratesupport surface. A second gas distributor, preferably a center nozzle,is used and is positioned spaced apart from and above the substratesupport surface, and a third gas distributor delivers an oxygen-supplygas (e.g., O₂) to the chamber through the top of the housing in a regiongenerally centrally above the substrate. This is preferably achieved bypassing the oxygen through an annular orifice created between the centernozzle carrying the silane (and any other gases) and a hole in the topof the housing. In one embodiment the first gas distributor includesfirst and second sets of nozzles.

In one embodiment of the method of the present invention, an FSG film isdeposited from a process gas that includes silane, oxygen and SiF₄.Oxygen and SiF₄ are delivered together to the chamber through the firstset of nozzles, and silane (or silane and SiF₄) is delivered through thesecond set of nozzles. Mixing the SiF₄ with oxygen and introducing thiscombination through the first set of nozzles reduces equipmentcomplexity so cost can be reduced. Silane (or silane and SiF₄) is alsoinjected into the vacuum chamber from the second gas distributor toimprove the uniform application of the gases to the substrate over thatwhich is achieved without the use of the second gas distributor, andoxygen is delivered through the third gas distributor. In this way,oxygen is provided both from the sides through the first set of nozzlesof the first gas distributors, preferably mixed with SiF₄, and also inthe same region as silane above the substrate. Also, the passage of theoxygen through the annular orifice keeps reactive gases within thechamber from attacking the seals used between the top of the housing andthe body from which the center nozzle extends. This advantage isretained if silane is passed through the annular orifice and oxygenthrough the center nozzle.

Film thickness and dielectric constant uniformity is also enhanced byensuring that the temperature of the substrate remains uniform acrossthe substrate and using a source RF generator designed to achievesputtering uniformity.

One of the primary aspects of the method of the present invention is therecognition that it is very important to ensure the uniform distributionof oxygen entering the chamber. This is achieved by flowing oxygen bothfrom the top of the chamber and from the sides of the chamber.Additionally, by the appropriate configuration of the oxygen flow paththrough the top of the chamber, the oxygen can serve to protect thesealing element from deleterious effects of coming in contact withreactive gases such as fluorine.

In addition to the need to supply the gases to the substrate uniformly,it is necessary to use the correct proportion of the gases, for exampleO₂, SiH₄ and SiF₄, to deposit a stable film and achieve a minimumdielectric constant for that film. The proper flow rates for each willdiffer according to the particular chamber used. Accordingly, it is afurther aspect of the invention to test a variety of flow rateproportions to discover which set of flow rates provides a high qualitydielectric film with a minimum dielectric constant.

Other features and advantages of the invention will appear from thefollowing description in which the preferred embodiments have been setforth in detail in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exaggerated view illustrating the characteristic M-shaped,deposition thickness variation plot of the prior art;

FIG. 2 illustrates an improvement in the deposition thickness variationplot of FIG. 1 using the apparatus of U.S. patent application Ser. No.08/571,618;

FIG. 3 is a schematic cross-sectional view showing a deposition chambermade according to one embodiment of the invention;

FIG. 4 is a graph of dielectric constant versus oxygen flow fordifferent flow rate ratios of SiF₄ to silane;

FIG. 5 is a simplified view of an alternative embodiment of the centernozzle of FIG. 3 having three orifices; and

FIG. 6 is a view in the region of the center nozzle showing additionaloxygen passageways.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 3 illustrates a deposition chamber 2 comprising a housing 4, thehousing including a generally cylindrized dielectric enclosure 6surrounded by two sets of RF inductive coils 8, 9. Enclosure 6 could bemade of RF transparent materials other than a dielectric material. Coils8, 9 are powered by a pair of source RF generators 10, 11. Chamber 2also includes a water-cooled substrate support 14 having a substratesupport surface 16 within the vacuum chamber 18 defined within housing4. Surface 16 is used to support a substrate 20 within chamber 18.Substrate support 14 acts as a cathode and is connected to a bias RFgenerator 22 through a matching circuit 24. A generally cylindricalsidewall 30 of housing 4 connects the bottom 32 of housing 4 todielectric enclosure 6. Sidewall 30 acts as the anode.

Process gases are introduced to vacuum chamber 18 in the regionsurrounding substrate 20 through two sets of twelve equally spacednozzles 34, 34 a. Nozzles 34, 34 a are arranged in a ring-like patternand are fluidly coupled to gas manifolds 36, 36 a, respectively.Manifolds 36, 36 a are fed process gases from first and second gassources 35, 35 a through first and second gas controllers 37, 37 a andfirst and second gas feed lines 39, 39 a. Each nozzle 34, 34 a has anorifice 38 at its distal end. The orifices 38 of nozzles 34, 34 a arearranged above the periphery 40 of substrate support 14 and thus abovethe periphery 42 of substrate 20. Vacuum chamber 18 is exhausted throughan exhaust port 44.

The various components of chamber 2 are controlled by a processor (notshown). The processor operates under control of a computer programstored in a computer-readable medium (also not shown). The computerprogram dictates the various operating parameters, such as timing,mixture of gases, chamber pressure, substrate support temperature and RFpower levels.

The present invention improves upon the above-described structure byproviding an improved gas delivery component 65 positioned abovesubstrate 20. In a preferred embodiment, gas delivery component 65includes a gas pathway 70 formed in a body 72 mounted to the top 75 ofenclosure 6. A center nozzle 56 passes through an opening 74 formed intop 75. Nozzle 56 and opening 74 provide an annular orifice 76 in fluidcommunication with vacuum chamber 18 and gas pathway 70. A fluid seal 78is provided between body 72 and top 75. Gas thus proceeds throughpathway 70, into a region defined between body 72 and top 75 and boundedby fluid seal 78, and finally along annular orifice 76.

In a preferred embodiment, the apparatus of the present invention isused to deposit FSG films from silane, oxygen and SiF₄ precursor gases.In this embodiment, the present invention preferably supplies acombination of SiF₄ and oxygen from first gas source 35 for introductioninto chamber 18 through orifices 38 of nozzles 34. Doing so simplifiesthe delivery of these gases and helps reduce cost. Silane (SiH₄) ispreferably delivered into chamber 18 from second gas source 35 a,through second gas controller 37 a, and through nozzles 34 a. Inaddition, third gas source 58 is preferably used to introduce silane(or, for example, a mixture of silane and SiF₄) into chamber 18 fromabove substrate 20. In conjunction with this, oxygen is also directedinto chamber 18 from a position above substrate 20, but along a flowpath separate from the flow path of the silane through pathway 70 andannular orifice 76.

Oxygen can be mixed with a relatively stable gas such as SiF₄; however,due to the reactive nature of silane and oxygen, these components mustbe kept separate until their introduction into chamber 18. To accomplishthis, separate nozzles 34, 34 a are used in the region around substratesupport 14; also oxygen is introduced through gas pathway 70 formed in abody 72. Pathway 70 is coupled to an oxygen source 71 through an oxygencontroller 73. Third gas line 62 passes through body 72 and terminatesat center nozzle 56. By injecting oxygen in this way, gases, such asfluorine compounds, which could otherwise have a deleterious effect onfluid seal 78, are prevented from reaching the fluid seal by the washingeffect or scouring effect of the flowing oxygen. In other embodiments,gases other than oxygen which do not cause seal 78 to deteriorate canalso be used.

Another advantage of delivering oxygen through gas pathway 70 is thatoxygen has a relatively long residence time as compared to silane orsome other gases. Because of the short residence time of silane, whensilane is introduced through orifice 76 it may dissociate relativelyquickly leading to particle formation within the orifice and upstream ofthe orifice in pathways 70. Molecular oxygen has a longer residence timethan silane, Thus, this is not a problem when oxygen is deliveredthrough orifice 76 instead.

Depositing FSG films in this manner results in stable films(substantially no HF or H₂O outgassing at temperatures up to 450° C.)having dielectric constants of less than 3.5 and even less than 3.4 or3.3. These low dielectric constant values are achieved in a generallyuniform manner over substrate 20. The uniform reduction of thedielectric constant is important because as device sizes are reduced,capacitance between closely spaced conductors will naturally increase.To reduce the capacitance, and thus speed up operation of the devices,the dielectric constant of the deposited dielectric film must bereduced.

In conjunction with the uniformity of gas distribution using thestructure discussed above, uniform dielectric constants are alsodependent upon temperature uniformity across substrate 20 and sputteringuniformity. See, for example, U.S. patent application Ser. No.08/641,147, filed Apr. 25, 1996, entitled “Substrate Support withPressure Zones Having Reduced Contact Area and Temperature Feedback,” ofinventors B. Lue, T. Ishikawa, F. Redeker, M. Wong and S. Li andassigned to Applied Materials, Incorporated for a description ofstructure which can be used to achieve more uniform temperaturedistributions along substrate. U.S. patent application Ser. No.08/389,888, filed Feb. 15, 1995, entitled “Automatic Frequency Tuning ofan RF Power Source of an Inductively Coupled Plasma Reactor” and U.S.patent application Ser. No. 08/507,726, filed Jul. 26, 1995, entitled“Plasma Source with an Electronically Variable Density Profile,” alsoassigned to Applied Materials, Incorporated, teach structure forenhanced sputtering uniformity. The disclosures of all three of theseapplications are incorporated by reference.

Varying the total flow of SiF₄ and silane affects deposition rate andthus throughput. High throughput requires high bias power from biaspower source 22 to create high sputtering and high etching rates. Highbias power, and thus high throughput, is possible only if temperatureuniformity across substrate 20 is achieved since speed of etching isstrongly affected by the temperature of the substrate.

The determination of the amounts of SiF₄, silane (SiH₄) and oxygen to beused creates an entire new layer of complexity. Assuming the total flowrate of silicon (e.g., from SiH₄ and SiF₄) remains constant, it isbelieved that several basic statements can be made regarding the use ofthese various components. If too little oxygen is used, the depositionrate drops dramatically thus making the process much too inefficient.Too little oxygen can leave the film silicon rich with excess freefluorine incorporated into the film. If too much oxygen is used, theresulting film becomes more USG and the dielectric constant becomeshigh. If too much SiF₄ is used, aging problems can result; agingproblems result because over time the fluorine, which is not boundtightly in the complex chemistry of the resulting film, gets releasedcausing deterioration of the device. Too much silane will cause the filmto behave more like USG and thus result in a dielectric constant at anundesirable level.

The optimal amounts of oxygen, SiF₄ and silane at the substrate surfaceare the stoichiometric proportions. However, flowing stoichiometricproportions of the gases into deposition chambers, including chamber 2and other deposition chambers, would result in gas proportions at thesubstrate surface which are not the stoichiometric proportions. Theactual proportions of the gas flowing into the deposition chamber neededto achieve stoichiometric proportions at the substrate surface will varyfrom the stoichiometric proportions at least in part according to thestructure of the specific chamber. The more efficient the chamber, theless gas is wasted so that gas flow rates closer to the stoichiometricamounts can be used.

To determine the proper relative flow rates of SiF₄, silane and oxygenfor a particular chamber to achieve the desirable dielectric constantbelow 3.5, preferably below 3.4 and more preferably below 3.3, theproportions of the three components could be varied in any desiredmanner to create a number of dielectric films on substrates 20; thedielectric constant at different positions along each dielectric filmcould then be measured. However, some limits in the relative amounts arein order. The percentage of SiF₄ should be between about 40% to 60% ofthe total silicon-supplying gas to reduce or eliminate the problemsresulting from too much or too little SiF₄ and silane. Oxygen should bebetween about 60% to 100% of the total silicon-supplying gas.

FIG. 4 illustrates the results of a set of tests conducted varying theratios of SiF₄ to silane to oxygen. It was found that by selecting atotal reactive gas flow rate, that is a flow rate for the combination ofSiF₄ and silane (which results in a constant amount of silicon),dividing that total between SiF₄ and silane to arrive at variousproportions of SiF₄ and silane, and then, using those proportions,varying the oxygen flow, the graph shown in FIG. 4 of dielectricconstant to oxygen flow was created. This type of graph provides veryuseful data.

Plot A, resulting from 44 sccm SiF₄ to 36.4 sccm silane, results in adielectric constant which varies from 3.4 at an oxygen flow of about 62sccm to about 3.8 at an oxygen flow rate of about 110 sccm. It is notclear from this graph where the minimum dielectric constant would be forthis ratio of SiF₄ to silane. It appears, however, that the minimumwould occur at an unacceptably low oxygen flow rate. Plot B, having ansccm flow rate ratio of SiF₄ to silane of 36 to 44.4 provides the lowestdielectric constant: about 3.2 at an oxygen flow of 60 sccm. Plots C andD have minimum dielectric constants of about 3.5 and 3.6 respectively.From this graph it is clear that for these particular ratios of SiF₄ tosilane, the ratio for Plot B provides the lowest dielectric constantwith oxygen flow being at an acceptable level. Reviewing plots A and Bsuggests that a proportion of SiF₄ to silane between the proportions forthese two plots may yield a lower dielectric constant than achievablewith the proportion for plot B.

Accordingly, the present invention provides a useful and efficient wayof determining how to achieve films with low dielectric constants usingSiF₄ (or another fluorine-supplying gas) and silane chemistry to achievethe reduced dielectric constants. While the above-described method ofchoosing a single total reactive gas flow rate for each of the tests ispresently preferred, other methods for the orderly gathering ofdielectric constant information may also be pursued. For example, it maybe desired to allow all three variables to change within the overallparameters.

In use, a film having a low dielectric constant can be deposited onsubstrate 20 by first determining the appropriate flow rates of SiF₄,silane and oxygen, typically in the manner discussed above by plottingthe results of different tests. Once the desired rate for the particularchamber has been determined, silane is introduced into chamber 18 fromsecond gas source 35 a, a mixture of silane and SiF₄ is introduced intochamber 18 from third gas source 58, oxygen is introduced into thechamber from oxygen source 71, and a mixture of oxygen and SiF₄ isintroduced into chamber 18 from first gas source 35. Argon is alsointroduced from first and third sources 35, 58. Deposition uniformity isalso aided by insuring that the temperature of substrate 20 is uniformlycontrolled over its surface and by the use of a variable frequencysource RF generators 10, 11 to help achieve uniform sputtering.

The above-described embodiment has been designed for substrates 20having diameters of 8 inches (20 cm). Larger diameter substrates, suchas substrates having diameters of 12 inches (30 cm), may call for theuse of multiple center nozzles 56 a as illustrated in FIG. 5 by thenozzle assembly 56′. In such embodiments the deposition thicknessvariation plot would likely have a three-bump (as in FIG. 3), afour-bump or a five-bump shape. The particular shape for the depositionthickness plot would be influenced by the type, number, orientation andspacing of center nozzles 56A and orifices 64.

In addition to orifice 76, oxygen may also be directed into chamber 18through a number of downwardly and outwardly extending passageways 80 asshown in FIG. 6. Each passageway 80 has an orifice 82 where oxygenenters into chamber 18. If desired, other gases, such as argon, may bemixed with one or both of the silane passing through orifice 64 oroxygen passing through annular orifice 76 or orifices 82.

Modification and variation can be made to the disclosed embodimentswithout departing from the subject of the invention as defined in thefollowing claims. For example, center nozzle 56 could be replaced by ashower head type of gas distributor having multiple exits or a circulararray of gas exits. Similarly, nozzles 34, 34 a or 56 a could bereplaced by, for example, a ring or ring-like structure having gas exitsor orifices through which the process gases are delivered into chamber18. While separate nozzles 34, 34 a are preferred, a single set ofnozzles 34 could be used to supply silane and SiF₄ but not oxygen.Orifice 76 can include a plurality of small apertures arranged in acircular fashion around center nozzle 56 rather than an annular ring.Also, oxygen source 71 and third gas source 58 could be switched so thatsource 71 becomes connected to nozzle 56 and source 58 becomes connectedto pathway 70.

Additionally, gases besides silane, oxygen and SiF₄ can be employed.Other silicon sources, such as tetraethyloxysilane (TEOS), other oxygensources, such as N₂O, and other fluorine sources such as C₂F₆CF₄ or thelike, may be used. Also, the chamber of the present invention can beused to deposit other halogen-doped films, USG films, low k carbon filmsand others. In some of these embodiments, e.g., some embodiments inwhich low k carbon films are deposited, oxygen may not be included inthe process gas. Thus, other gases, e.g., nitrogen, may be introducedthrough orifice 76 in these embodiments. These equivalents andalternatives are intended to be included within the scope of the presentinvention. Other variations will be apparent to persons of skill in theart. Accordingly, it is not intended to limit the invention except asprovided in the appended claims.

What is claimed is:
 1. A method for depositing a film onto a substratewithin a deposition chamber comprising the steps of: injecting a firstprocess gas having a plurality of gas components into the chamber at aplurality of positions surrounding a substrate within the chamber;injecting a second process gas into the chamber at a first region spacedapart from and located generally centrally above the substrate; andinjecting an oxygen-supplying gas into the chamber at a second regionspaced apart from and located generally centrally above said substrate,wherein the plurality of gas components of the first process gas includefirst gas components and second gas components which are different gascomponents and which are injected into the chamber separately via afirst set of nozzles for injecting the first gas components and a secondset of nozzles for injecting the second gas components at the pluralityof positions surrounding the substrate within the chamber.
 2. The methodof claim 1 wherein the first process gas is injected into the chambervia orifices at the plurality of positions surrounding the substrate,the orifices being located higher in elevation than the substrate. 3.The method of claim 1 wherein the second process gas comprises SiH₄. 4.The method of claim 3 wherein the second process gas further comprisesSiF₄.
 5. The method of claim 1 wherein the first process gas is injectedinto the chamber via a plurality of nozzles equally spaced about thecenter of the substrate.
 6. The method of claim 1 wherein SiH₄ isinjected via the first set of nozzles and oxygen is injected via thesecond set of nozzles.
 7. The method of claim 6 wherein SiF₄ is injectedvia the second set of nozzles in addition to the oxygen.
 8. The methodof claim 1 wherein the second process gas is injected into the chambervia a plurality of orifices.
 9. The method of claim 1 wherein the secondprocess gas is injected into the chamber via a single orifice.
 10. Themethod of claim 1 wherein the oxygen-supplying gas is injected into thechamber via a plurality of orifices.
 11. The method of claim 1 furthercomprising forming a plasma in the chamber from the process gases.
 12. Amethod for depositing a film onto a substrate within a depositionchamber comprising the steps of: injecting a first process gas having aplurality of gas components into the chamber at a plurality of positionssurrounding a substrate within the chamber; injecting a second processgas into the chamber at a first region spaced apart from and locatedgenerally centrally above the substrate; and injecting anoxygen-supplying gas into the chamber at a second region spaced apartfrom and located generally centrally above said substrate, wherein thechamber includes a top, and wherein the second process gas is injectedinto the chamber via a gas distributor having an extension passingthrough the top into the chamber and terminating within the chamberinwardly away from an inner surface of the top, and wherein theoxygen-supplying gas is injected into the chamber at the inner surfaceof the top.
 13. The method of claim 12 wherein the first process gas isinjected into the chamber via orifices at the plurality of positionssurrounding the substrate, the orifices being located higher inelevation than the substrate.
 14. The method of claim 12 wherein thesecond process gas comprises SiH₄.
 15. The method of claim 14 whereinthe second process gas further comprises SiF₄.
 16. The method of claim12 wherein the first process gas is injected into the chamber via aplurality of nozzles equally spaced about the center of the substrate.17. The method of claim 12 wherein the first process gas is injectedinto the chamber via a first set of nozzles and a second set of nozzles,the first set of nozzles being fluidly isolated from the second set ofnozzles.
 18. The method of claim 17 wherein SiH₄ is injected via thefirst set of nozzles and oxygen is injected via the second set ofnozzles.
 19. The method of claim 18 wherein SiF₄ is injected via thesecond set of nozzles in addition to the oxygen.
 20. The method of claim12 wherein the second process gas is injected into the chamber via aplurality of orifices.
 21. The method of claim 12 wherein the secondprocess gas is injected into the chamber via a single orifice.
 22. Themethod of claim 12 wherein the oxygen-supplying gas is injected into thechamber via a plurality of orifices.
 23. The method of claim 12 furthercomprising forming a plasma in the chamber from the process gases.
 24. Amethod for depositing a film onto a substrate within a depositionchamber comprising the steps of: injecting a first process gas having aplurality of gas components into the chamber at a plurality of positionssurrounding a substrate within the chamber; injecting a second processgas into the chamber at a first region spaced apart from and locatedgenerally centrally above the substrate; and injecting anoxygen-supplying gas into the chamber at a second region spaced apartfrom and located generally centrally above said substrate, wherein thechamber includes a top, and wherein the second process gas is injectedinto the chamber via a gas distributor having an extension passingthrough the top into the chamber and terminating within the chamber,wherein the top includes an access opening therethrough, wherein the gasdistributor for the second process gas includes a body mounted to thetop overlying the access opening, wherein a fluid seal is capturedbetween the body and the top and circumscribes the access opening, andwherein the oxygen-supplying gas is injected into the chamber via apathway fluidly coupled to the fluid seal and preventing gas from withinthe chamber from contacting the seal.